1. Field of the Invention
The invention relates to an amplifier, especially a differential amplifier.
2. Discussion of the Background
By convention, differential amplifiers comprise at least two transistors, which are connected to form a differential pair. However, such simple amplifiers are characterized by poor linearity. The linearity of amplifiers can be improved through the introduction of resistors into the emitter path. However, this reduces the efficiency of the amplifier. Moreover, at the same time, the amplification factor is reduced.
An amplifier based on 4 transistors, a Caprio's Quad, is also known. Such an amplifier is characterised by a high linearity and an adjustable amplification factor. For example, “Precision differential voltage-current converter, Raimondo Caprio, Electronics Letters, Vol. 9, No. 6, 1973” shows such a differential amplifier.
Especially at high frequencies, an amplifier according to Caprio demonstrates unfavourable behavior.